Norton keeps blocking trojan.gen.2

Hi - first time on here, so apologies if I've posted in the wrong place!

Whenever I first connect to the internet I get a message that auto-protect has blocked trojan.gen.2. I've run several full system scans, Norton power eraser and scanned with Malawarebytes and all seems fine.

Do I have a virus here, or is it just the case that my PC keeps being attacked?!

Thanks for your help!

Ian